Die assembly for crimping a shielded cable



p 25, 1962 D. DIBNER 3,055,412

DIE ASSEMBLY FOR CRIMPING A SHIELDED CABLE Filed July 22, 1954 INVENTOR..DAVID DIBNER HIS ATTORNEY United States Patent Filed July 22, 1954,Ser. No. 444,991 1 Claim. (Cl. 153-1) My invention relates to a novelcrimp for securing connectors or ferrules to a coaxial cable.Ordinarily, these connectors are crimped with a die having interlockingteeth or leaves operating in corresponding grooves which producecircumferential and staggered indentations on the outer surface of theconnector. If one end, or possibly both ends of the ferrule are locatedover one of the grooves in the die, the ferrule will bend into thisgroove under the crimping force and result in a flare or bell beingformed in the connector edge. This condition is objectionable becausewiring assemblies or harnesses employing large numbers of such ferrulesare frequently packed tightly together, increasing the possibility ofthe sharp, flared edge of the installed ferrule cutting into theadjacent cable and producing a short circuit. The trend towards closelypacking cables is a result of greater miniaturization in electronicdesign. This problem is almost solely confined to the smaller shieldedor coaxial cables where the cables are unable to resist the cutting ofthe flared ferrules.

At present, two types of die crimps are commercially available for suchconnectors. One employs symmetrical grooves which close down on the endsof the connectors. Pockets are laterally provided into which the excessmaterial fiows to form a flash, causing a cross-sectional configurationof the cable that is almost oval, with two flash elements extendingtherebeyond. I have found this type of crimp to be objectionable, forthe connector should not provide an extension or edge which could dodamage to an adjacent cable.

The other present type avoids the flash by providing a hexagonal crimp.I find that this type of crimp is objectionable because the six cornersof the connector provide sharp points which also can damage adjacentwires in a harness assembly.

Accordingly, the principal object of my invention is to produce a crimpfor a coaxial cable connector which will reduce or eliminate the presenttype of belling, flaring or ovalizing, which exposes sharp edges, orpoints which damage adjacent cables.

These and other objects of my invention are accomplished and my newresults obtained as will be apparent from the device described in thefollowing specification, particularly pointed out in the claim, andillustrated in the accompanying drawing, in which:

FIG. 1 is a side elevation of a pair of crimping dies in open positionfor incorporating my invention.

FIG. 2 is a longitudinal sectional view of the same.

FIG. 3 is a side elevation of the dies of FIG. 1 in closed position.

FIG. 4 is a longitudinal sectional View of the same.

FIG. 5 is a perspective view of the upper die of FIG. 1.

FIG. 6 is a side elevation of the crimp forming my invention on acoaxial cable connector.

In the drawing FIG. 1, there is illustrated a pair of die bases 10 and12, each provided with plate-like teeth or leaves, namely 14 and 16,respectively, which when the dies are closed, mate or interlock witheach other into slots 15 and 17, respectively, providingsemi-cylindrical crimping surfaces 18 and 19 outlining a hole 20 whichis less than the original diameter of the connector being crimped. Asshown in FIGS. 5 and 6, the crimp 21 caused by leaves 14, and crimp 22caused by leaves 16, compress the connector 23 around the shielded wires24 of the coaxial cable 25.

Beyond the crimping teeth 14 and 16, there are provided correspondinggrooves 26 and 28, respectively, concentric with and larger than hole 20for swaging the end surfaces 27 of the connector into cylindricalposition during crimping. The dies are limited in their closing movementby flat surfaces 30 and 32, respectively, provided on opposite spacesthereof.

When the annealed copper ferrule 23 is placed over the shielding wire 25of the coaxial cable 26 and then between the dies 10 and 12 in theiropen position, the ferrule is located by the operator placing itapproximately over the surfaces 18. When the dies 10 and 12 are pressedtogether by the accommodating installation tool, not shown, the ferruleis first squeezed or crimped by the edges of the interlocking surfaces18 and 19. When the ferrule is under compression from the teeth, ittends to buckle as a result of the deformation being applied to it. Thisnormally results in the flaring, flashing or belling which haspreviously been considered objectionable. However, in my new device, theends of the ferrule are contained and controlled by the swaging grooves26 and 28 which reduce the diameter of the ferrule enough to close theferrule around the cable, but in such a way as to provide a smooth,cylindrical appearance at the ends of the ferrule and to avoid anybelling or flashing as was previously experienced. Note that in mydesign, not only are flash pockets avoided in the swaging grooves whichwould allow room into which the ferrule would expand and thereforeresult in flash projection, but the swaging grooves are provided withsharp edges which maintain the ferrule in a cylindrical form withoutallowing it to ovalize or flash. This design maintains the features andadvantages of the interlocking teeth type of ferrule crimping die andalso achieves a method of reducing the diameter of a cylindrical ferruleby swaging without deforming the ends of the ferrule in such a way as tobe damaging to conductors placed adjacent to it.

I have thus described my invention, but I desire it understood that itis not confined to the particular forms or uses shown and described, thesame being merely illustrative, and that the invention may be carriedout in other ways without departing from the spirit of my invention,and, therefore, I claim broadly the right to employ all equivalentinstrumentalities coming within the scope of the appended claim, and bymeans of which objects of my invention are attained and new resultsaccomplished, as it is obvious that the particular embodiments hereinshown and described are only some of the many that can be employed toattain these objects and accomplish these results.

I claim:

A pair of crimping dies for crimping a connector to a shielded cable,each die comprising a plurality of extending interspaced slots andleaves, each of said slots accommodating a leaf from the mating die,said leaves provided with semi-cylindrical crimping surfaces, said diesprovided with semi-cylindrical grooves on a side of the dies, forcompressing the uncrimped ends of the connector body in a perfectlycylindrical shape, concentric with and slightly larger than the crirnpedsurfaces, said die parts compressing a cylindrical connector to acoaxial cable into a cylindrical shape free of flaring, belling andflashing.

References Cited in the file of this patent UNITED STATES PATENTS 4Richardson July 5, 1910 Carlson Sept. 26, 1944 Lepkowski Dec. 11, 1945Dupre Dec. 28, 1948 Bergan Aug. 30, 1949 Macy May 26, 1953 Pierce Oct.26, 1954 Wells Mar. 15, 1955 FOREIGN PATENTS Germany Apr. 24, 1925

